Am I Cracking Up?

[FSNut01]

We just had a 30x40 barn built and overall the builder did an excellent job on everything. The quality of materials and workmanship are top notch on just about everything they did. I am concerned about the floor though and am seeking input from anyone with concrete knowledge.

There is tubing under the slab, it's 4-5" thick and 4000 psi mix. It was poured 21 days ago and saw cut the next day. It was sealed the day of the pour. I am starting to notice what looks like cracks beginning at the support poles and they are not following the saw cuts as I would have hoped. Is there anything I can do to stop them before they get any worse? Should I try to get the saw cuts all the way to the poles? I am planning on boxing in the poles and installing air/elec in the enclosures so an additional cut perpendicular to the cracks wouldn't be noticeable.

Thanks.

 

[1ownerT]

There should have been a bond break at each column, something like roofing felt paper would have worked. Better yet would have been to box out the columns when the slab was poured, with the corners meeting at the saw cuts, coming back and pouring in the box outs with bond breaks.
You could extend the saw cuts to the columns with a small hand held grinder with a masonry wheel and if they haven't extended too far make a diamond saw cut around the columns.

One thing is guaranteed with concrete...it will crack.

 

[dcs Inc]

Normally the contractor will isolate these off with a cold joint and expansion like this.

These are hydration cracks and may or may not open up.

 

[FSNut01]

Thanks for the fast replies.

I had a feeling that he should have isolated the columns and actually mentioned it to him before he poured the floor but he said he never does and hadn't had any problems with them in the past. There's a massive footer under the column and he said that because of it there wouldn't be any cracking issues. So much for that theory!

You could extend the saw cuts to the columns with a small hand held grinder with a masonry wheel and if they haven't extended too far make a diamond saw cut around the columns.

I can cut the existing ones to the columns. If I were to do a diamond shaped cut around the columns how deep should I go?

 

[dcs Inc]

As deep as you can. The shrinkage cracks have already formed and maybe cutting deeply wil help.